Phosphonium compounds

ABSTRACT

A di lower alkyl phosphite acrylamide or methacrylamide, preferably with formaldehyde and tetrakis (hydroxymethyl) phosphonium halide are reacted to form a compound of the formula WHERE R1 and R2 are lower alkyl R3 is hydrogen or methyl and R4 is hydrogen or methylol. The compounds are useful as fire retardants, particularly in textiles, paper and other forms of cellulosic fibers as well as synthetic fibers.

United States Patent Moretti I54] PHOSPHONIUM COMPOUNDS [72] Inventor: IPeter A. Moretti, Cranston, R.l.

[73] Assignee: U.S. Oil Company, Incorporated,

' East Providence, R.I.

[22] Filed: Oct. 20, 1970 [2i] Appl. N0.: 82,496

[56] References Cited UNITED STATES PATENTS 7/1957 Coover et al...260/984 X 3/1968 Zahir ..260/943 1151 3,699,192 1451 Oct. 17, 1972Primary Examiner-Lewis Gotts Assistant Examiner-Anton H. SuttoAttorney-Cushman, Darby & Cushman ABSTRACT A di lower alkyl phosphiteacrylamide or methacrylamide, preferably with formaldehyde and tetrakis(hydroxymethyl) phosphonium halide are reacted to form a compound of theformula R20 R3 R where R and R are lower alkyl R is hydrogen or methyland R is hydrogen or methylol. The compounds are useful as fireretardants, particularly in textiles, paper and other forms ofcellulosic fibers as well as synthetic fibers.

7 Claims, No Drawings PHOSPHONIUM COMPOUNDS The present inventionrelates to novel organic phosphorous compounds and their use as fireretardants.

Tetrakis (hydroxymethyl) phosphonium chloride (and the correspondingbromide) is a known fire retardant for cellulose, textiles, etc.However, it imparts an undesirable after odor. Furthermore, it is not aseasily activated as would be desired. Additionally it is relativelyexpensive for the amount of phosphorus contributed as a fire retardant.N-hydroxymethyl-3- (dimethylphosphono) propionamide is also known as afire retardant, however, its use with cellulose requires the addition ofa resin such as melamine-formaldehyde resin to react with the celluloseand give durability.

It is an object of the present invention to prepare a novel phosphorouscompound.

Another object is to develop improved fire retardant compositions.

Still further objects and the entire scope of applicability of thepresent invention will become apparent from the detailed descriptiongiven hereinafter; it should be understood, however, that the detaileddescription and specific example, while indicating preferred embodimentsof the invention, are given by way of illustration only, since variouschanges and modifications within the spirit and scope of the inventionwill become apparent to those skilled in the art from this detaileddescription.

It has now been found that these objects can be attained by reacting adi lower alkyl phosphite with acrylamide or methacrylamide. The producteither in separated or unseparated form is then reacted with tetrakis(hydroxymethyl) phosphonium halide, e. g. tetrakis (hydroxymethyl)phosphonium chloride or tetrakis (hydroxymethyl) phosphonium bromide.Preferably there is added a formaldehyde source, e. g. aqueousformaldehyde, alcoholic formaldehyde, trioxane or paraformaldehyde priorto adding the phosphonium halide. If the formaldehyde is omitted lessreactivity of the product with cellulose and other polymers is noted atlow ratios of phosphonium halide to the reaction product of phosphiteand unsaturated amide. If desired all of the reactants can be employedinitially, e. g. (l) phosphite, (2) amide and (3) phosphonium halide or(1) phosphite, (2) amide, and (3) formaldehyde and (4) phosphoniumhalide, but the yields of the product are not as high as when thereaction is carried out in the preferred order.

The products of the invention have the formula where R and R are loweralkyl, R is hydrogen or methyl and R is hydrogen or methylol. When aformaldehyde source is used as a reactant R is methylol and where theformaldehyde source is omitted R is hydrogen.

As starting dialkyl phosphites there can be used, for example, dimethylphosphite, diethyl phosphite, dipropyl phosphite, diisopropyl phosphite,methyl ethyl phosphite.

The secondary phosphite and amide are reacted in equimolar proportions.The reaction can be carried out in the presence or absence of acatalyst, preferably a non acidic catalyst is used such as metallicsodium, potassium and lithium, alkali metal amides such as sodamide,alkali metal hydrides, such as sodium hydride, potassium hydride andlithium hydride, alkali metal alcoholates and phenolates, e. g. sodiummethylate, potassium methylate, sodium ethylate, sodium propylate,potassium isopropylate and sodium phenolate, sodium hydroxide, anionexchange resins, secondary and tertiary amines, alkali metal salts ofthe secondary phosphites, etc. The reaction is preferably carried out ina solvent, e. g. water or more preferably an alcohol such as methylalcohol, ethyl alcohol, propyl alcohol or isopropyl alcohol. Mixtures ofwater and alcohol can be used. The reaction is carried out at reflux atpH of8 :1 for 3 to 5 hours.

' Instead of reacting the secondary phosphite and amide in situ therecan be employed preformed amides of the type shown in Johnston U.S. Pat.No. 2,754,320,

e. g. 3-(dimethylphosphono) propionamide 3- (diethylphosphono)propionamide, 3- (dipropylphosphono) propionamide, 3-

(diisopropylphono) propionamide, S-(methyl ethyl phosphono)propionamide, 3-(dimethyl-phosphono)- Z-methyLpropionamide,3-(diethylphosphono)-2- methyl-propionamide.

When a formaldehyde source is employed it can be used in an amount of to2 moles per mole of starting acrylamide or methacrylamide (or 1 to 2moles per mole of preformed 3-(dialkylphosphono) propionamide), but ispreferably used in an amound of I A moles per mole of amide. There canbe employed the same solvents as mentioned earlier, e. g. water andalcohols. Alternatively the formaldehyde can be prereacted as shown inZahir U.S. Pat. No. 3,374,292 to form N-hydroxy-methyl amides such asN-hydroxy e h lfirtil methy zph snhpngl, top qn mi ehydroxymethyl-3-(diethylphosphono) propionamide,N-hydroxymethyl-3-)di-isopropylphosphono) propionamide,N-hydroxymethyl-3- (dipropylphosphono) propionamide,N-hydroxymethyl-3-(methyl ethyl phosphono) propionamide, N-hydroxymethyl-3-(dimethylphospono)-2-methylpropionamide,N-hydroxymethyl-3- (dipropylphosphono)-2-methylpropionamide, N-sesquimethylol-3-(dimethylphosphono)-propionamide or the corresponding amidehaving an average of l A methylol groups per nitrogen atom.

The reaction with the phosphonium halide, e. g. tetrakis (hydroxymethyl)phosphonium chloride (THPC) is carried out using a ratio of 0.1 to 2moles of phosphonium halide per amide group, the preferred ratio being 1l. For best results the solution of amide or (methylol amide)intermediate in the alcohol and/or water after stripping out a portionof the solvent. The weight ratio of the amide or (methylol amide)intermediate to THPC can be from 1 0.1 up to l 2, or even higher, e. g.I :5. The preferred ratio is l 1.

Examples of compounds within the present invention are N-tetrakis(hydroxymethyl) phosphonium 3- (dimethylphosphono) propionamide,N-tetrakis (hydroxymethyl) phosphonium 3-(diethylphosphono)propionamide, N-tetrakis (hydroxymethyl) phosphonium-3-(methyl ethylphosphono) propionamide, N- tetrakis (hydroxymethyl) phosphonium-3-(dipropylphosphono) propionamide, N-tetrakis (hydroxymethyl)(diisopropylphosphono) propionamide, N-tetrakis (hydroxymethyl)phosphonium-3- (dimethylphosphono)-2-methylpropionamide, N-tetrakis(hydroxy methyl) phos-phonium-B- (dipropylphosphono )-2-methylpropionamide, N- tetrakis (hydroxymethyl) phosphoniumN-hydroxymethyl-3-(dimethylphosphono) propionamide, N- tetrakis(hydroxymethyl) phosphonium N-hydroxymethyl-3-(diethylphosphono)propionamide, N- tetrakis (hydroxymethyl) phosphoniumN-hydroxymethyl-3-(ethyl methyl phsophono) propionamide, N- tetrakis(hydroxymethyl) phosphonium N-hydroxymethyl-3-(dipropylphosphono)propionamide, N- tetrakis (hydroxymethyl) phosphoniumN-hydroxymethyl-3-(diisopropylphosphono) propionamide, N-

tetrakis (hydroxymethyl) phosphoniumN-hydroxymethyl-3-(dimethylphosphono)-2-methylpropionamide, N-tetrakis(hydroxymethyl) phosphonium N-hydroxymethyl-3-(dipropylphosphono)-2-methyl propionamide.

The products of the invention can be employed as fire retardants inaqueous or alcoholic solution and hence can be employed as they areprepared. Alternatively the solvent can be removed by evaporation todryness, preferably by vacuum stripping. When they are evaporated todryness they are usually viscous, tacky, water clear to yellowishmaterials. However, at higher mole ratios of the amide or methylol amideto phosphonium halide, e. g. 5 1, they are solids.

The fire retardant products of the present invention have less afterodor than tetrakis (hydroxymethyl) phosphonium chloride when applied.

The compounds of the present invention by themselves. also will crosslink with hydroxyl containing polymers such as cellulose and celluloseesters.

The products of the present invention are particularly useful as fireretardants for use in the textile field, e. g. with cellulosic fiberssuch as cotton and regenerated cellulose, cellulose acetate, cellulosepropionate, cellulose acetate-propionate, cellulose acetate butyrate,Dacron (polyethylene terephthalate)- cotton blends, etc. They can beused as fire retardants for plywood and paper.

Additionally they are useful as fire retardants and reactiveplasticizers in making polyurethanes and they are useful as fungicides,e. g. in treating textiles, the soil or plants, etc.

The can be used in mass spinning of polyesters, e. g. Dacron acrylicfibers. e. g. acrylonitrile-vinyl chloride copolymers (85:15) modacrylicfibers, nylon (polyamide fibers, e. g. nylon, 6,6 or nylon 6) to givefire proofing properties.

When treating textiles the compounds are employed in aqueous oralcoholic solution (e. g. methanol, ethanol, isopropanol) or aqueousalcohol, e. g. as a solution containing 80 percent solids although thesolids content of the solution is not critical. The compounds arenormally used in an amount (dry basis) of 5 40 percent, preferably 16 24percent of the weight of the textile.

phosphonium-3-' malamine, pentamethoxymethyl melamine and other triazineformaldehyde products, e. g. as set forth in Widmer US. Pat. No.2,197,357, u-rea formaldehyde, dimethylol dihydroxyethylene urea, glycolresins, dimethylol ethyl triazone and other triazones. These resins andresin precursors, however, can be omitted since the compounds of thepresent invention by themselves react with cellulose, for example, togive durability and cross linking.

In cross linking cellulose there can be used conventional initiators orcatalysts such as metal salts, e, g. zinc chloride, zinc nitrate,magnesium chloride, zinc borofluoride (ZnBF amine hydrochlorides, etc.The catalysts can be used, for example, in an amount of 0.5 30 percentby weight of the compounds of the invention. The compounds of thepresent invention are much more easily activated then tetrakis(hydroxymethyl) phosphonium chloride.

It will be appreciated that mixtures of compounds can be prepared andused, e. g. a mixture of N-tetrakis (hydroxymethyl)phosphonium-3-(dimethyl phosphono) propionamide and N-tetrakis(hydroxymethyl) phosphonium N-methylol-3-dimethyl phosphono)propionamide in mole ratio of l 0.1, e. g. l 1.

Unless otherwise indicated all parts and percentages are by weight.

EXAMPLE 1 There were added to a reactor 33.0 pounds of commercial 95 98percent methanol and 36.3 pounds of dimethyl hydrogen phosphite(dimethyl phosphite) and the mixture stirred. There was added 23.5pounds of acrylamide and the mixture heated to C. Next the temperaturewas raised to C. (reflux). The pH as maintained at 8.5-9 by the slowdropwise addition of 3375 ml. of 20 percent sodium m'ethylate inmethanol. The reflux and pH were maintained for 3 hours. The heatwasshut off and the intermediate product cooled to 45 C. Then 26.8 poundsof 37% aqueous formaldehyde were added slowly over about one half hour.The pH was adjusted to 7.5 8.0 with 375 ml. of 20 percent aqueous sodiumhydroxide. Reaction was continued at 60 65 C. for one hour whilemaintaining the pH at 7.5 8.0. The mixture was cooled to roomtemperature and vacuum stripped to 80 percent non volatile solids (NVS).

EXAMPLE 2 To parts of the final product of Example 1 there was slowlyadded 5 parts of tetrakis (hydroxymethyl) phosphonium chloride (THPC) inwater with stirring. The mixture was heated to F. and held at 120 --1 75F. for one half hour. The pH was about 4.0 5 .0. The product was cooledto 80 F. and drawn. If desired the product can be filtered.

EXAMPLE 3 To 83.4 parts of the final product of example 1 there wasslowly added 16.6 parts of 80 Tl-lPC in water with stirring and theprocedure of example 2 followed. The pH of the product was about 3.54.0.

EXAMPLE 4 The procedure of example 2 was repeated using 50 parts of theproduct of example 2 and 50 parts of 80 percent THPC in water. Theheating was at 120 130 F. The pH of the product was 2.5 3.0.

EXAMPLE 5 The procedure of example 1 was repeated except the 1 additionof formaldehyde was omitted to product N- tetrakis (hydroxymethyl)phosphonium-S- (dimethylphosphono) propionamide.

EXAMPLE 6 Five finishing formulations suitable for treating textiles, e.g. cotton, were prepared as follows:

Fire retardant product of example 3 30.0 parts Dimethylol dihydroxyethylene urea 10.0 parts 30% polyethylene emulsion 2.0 parts Urea 5.0parts Zinc nitrate hexahydrate 0.2 parts Water 52.8 parts Total: 100.0

Fire retardant product of example 3 30.0 parts Dimethyl ethyl triazone10.0 parts 30% polyethylene emulsion 2.0 parts Urea 5.0 parts Ammoniumchloride 0.4 parts Water 52.6 parts Total: 100.0

Textiles, e. g. cotton, are impregnated with any one of the compositionsof example 6(a) through (e) and then dried to give a flame proofproduct. Preferably the drying is carried out at a curing temperature,e. g. 225 F.

What is claimed is:

1. A compound having the formula R20 R5 R where R and R are loweralk-yl, R is hydrogen or methyl and R is hydrogen or methylol.

2. A compound according to claim 1 wherein R is hydrogen. I

3. A compound according to claim 2 wherein R and R are methyl.

4. A compound according to claim 3 wherein R is hydrogen.

5. A compound according to claim 1 wherein R is methylol.

6. A compound according to claim 5 wherein R and R are methyl.

7. A compound according to claim 1 wherein R is hydrogen.

2. A compound according to claim 1 wherein R4 is hydrogen.
 3. A compoundaccording to claim 2 wherein R1 and R2 are methyl.
 4. A compoundaccording to claim 3 wherein R4 is hydrogen.
 5. A compound according toclaim 1 wherein R4 is methylol.
 6. A compound according to claim 5wherein R1 and R2 are methyl.
 7. A compound according to claim 1 whereinR4 is hydrogen.